JPS59170708A - Measuring method of surface area - Google Patents

Abstract

PURPOSE:To carry out measurement speedily by dipping a substrate to be plated in an electroplating solution, measuring the polarization value of the substrate in open circuit state right after a specific amount of charge is given instantaneously, and calculating the electric capacity of an electric double layer. CONSTITUTION:A substrate 1' whose surface area S is already known is dipped in the electroplating solution under constant-temperature and constant-stirring condition. Then, the substrate 1' is supplied with charge pulses from a capacitor 5 to give a specific amount of charge, obtaining the relational curve of the polarization value eta of the substrate 1' and time (t) on a potentil difference recorder 8 through a reference electrode 2. The electric double layer capacity of the substrate 1' is divided by the surface area S to calculate the electric double layer capacity per unit area. Then, the polarization value of the effective surface of a plated part of a substrate 1 whose surface area is not known is measured in the electroplating solution on the same temperature and stirring condition. The electric double-layer capacity of the substrate 1 is divided by the electric double layer capacity per unit area to calculate the effective area of the plated part of the substrate 1.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for measuring the effective surface area of a plated portion of a plate by applying a coulostat, and more specifically, relates to a method for measuring the effective surface area of a plated portion of a plate by applying a coulostat. This invention relates to the 111 method for surface area, which allows the effective surface area of a plated part to be quickly determined in liquid.

[Technical background of the invention and its problems] In order to obtain an excellent menchie film in hypochondriac menkie, suitable i.
It is necessary to carry out electrical meso-ki at a current density of 1-. This is because the current density has a great influence not only on the plating speed but also on the appearance, strength, electrodepositivity, etc. of the coating.

In order to determine the appropriate current density, the exposed area of the plate (into the coating solution), i.e. the effective surface area of the part to be plated, is usually determined in advance before coating starts. However, if the shape of the part to be polished is rough, it is extremely difficult to measure the effective surface area.

For example, semi-additive method) 1 (printed wiring) 1
In the case of electric polishing for V-boards, the part to be plated has a complicated wiring shape, so it takes a lot of effort to find the exact effective surface area and determine the appropriate current density. The problem is that it requires effort and time.

For this reason, conventionally, in electroplating of printed wiring boards,
From the standpoint of placing emphasis on productivity, there was a tendency to omit the measurement of the effective surface area of the part to be plated. That is, the effective surface area of the part to be plated was often determined by visual judgment based on the aquatic experience of field workers. However, in cases where the wiring shape is extremely complex, it is impossible to conduct JG to avoid errors in visual judgment of l=I, and this may result in poor electrical conductivity or insufficient plating thickness due to inappropriate current density, resulting in poor quality control. It was surrounded by four walls.

In order to solve this problem, attempts have been made to develop a graphic processing device that combines a television camera and a computer. However, this device is very time-consuming and expensive, so it lacks practicality and has not been a substantial solution to the Kitaki problem.

[Object of the Invention] An object of the present invention is to provide a practical method for rapidly measuring the effective surface area of a part to be cleaned, and thereby to obtain an appropriate current density in electric cleaning. V [Summary of the Invention] As a result of intensive research in order to achieve the object stated in item L, the inventors have discovered that various ions in the plating solution are present on the effective surface of the plated portion of the substrate immersed in the electroplating solution. The capacitance of this electric double layer is exactly proportional to the effective surface area under certain conditions, and the volume of the electric double layer is proportional to the polarization of the substrate. (It can be found by setting if to i1+11,
7II-IL completed the invention.

The effective area of the part to be plated according to the present invention is determined by immersing the substrate to be plated in an electric coating solution (immediately after applying a predetermined amount of charge to the plate) 1 ( The polarization value of the plate is measured with an open circuit Y-fish, and the polarization value is
The method is characterized in that the effective surface area is measured by calculating the volume of hair debris in the Qi Ertun layer.

In the measurement method of the present invention, a predetermined amount of electric charge is instantaneously applied to a substrate immersed in an electromagnetic liquid, and then the polarization value of the substrate is immediately measured in an open circuit state. The effective area of the part to be repaired is determined from the value of the electric double layer capacitance (Cd) obtained by calculating the electric double layer capacity (Cd). That is, in the present invention, the so-called coulostat method (4'8 Publication 1986-128) is used to determine the electric double layer capacitance (Cd).
No. 12, published in Publication No. 58-11101) is used.

Hereinafter, the surface area measuring method of the present invention will be explained with reference to the drawings.

The first figure is Coolostala l-? used in the invention? An example of the arrangement of the ili source, charging system, working electrode, reference electrode, counter electrode, etc. in J.

In the figure, a substrate 1 or 1' serving as a working electrode, a counter electrode 3, and a reference pji 2 are arranged in a plating bath 4. )
, (A capacitor 5 is used as a charging system that applies 17 charge pulses to the plate 1 or 1 degree. This capacitor 5 is charged with a predetermined 11 charges by connecting it to a power source 6 and a relay 7. , by changing the relay 7 and J, the electric charge can be instantaneously transferred to the substrate l or 1° via the counter electrode 3. At this time, the polarization (1t(η The change in is measured by the reference electrode 2 and recorded by the potentiometric recording device 8.

In the Coulostand method, the electric double layer capacitance (Cd) is determined as follows.

First, a substrate 1' whose surface area S is known in advance is immersed in an electroplating solution at a constant temperature and under constant stirring conditions.

After that, a charge pulse is applied to the substrate 1° from the capacitor 5 to generate a predetermined amount of charge.
Using a potentiometric recording device (on δ8), the relationship curve between polarization value η of plate 1 and waiting time (1) is calculated. Equation (1) below is established between m'i and m'i.

Δq=ηocd, ,,,,, (1) ηo: J, s: Polarization value Cd of substrate 1' immediately after charge is applied to the vinyl plate Electric double layer capacitance 11-Δq of one substrate 1'':
2t; Electric vinyl board - Double Iai HH! The electric power η0 obtained is the fi of η when 1=0 of the polarization value η-waiting time curve.
It can be found from the value of η when extrapolated to t, i or 1 = 0, and Δq can be found from the product of the capacitor capacity of the charging system and its charging voltage, so from these values the formula ( 1), 31 CDs are immediately issued.

By dividing the value of Cd by the surface area S of the substrate 1', the electric waste volume per unit area of the substrate 1'
1(Cdo) is found.

Next, the electric double layer capacitance was determined by measuring the polarization value of the surface area of the surface to be thinned on the substrate with unknown surface area in the electrolytic thinning solution at the same temperature and stirring conditions as described in J.-1. (Cd) is calculated in the same manner as above, and by dividing this electric double layer capacitance (Cd) by the electric-soil layer capacitance per unit area (Cdo), the effective surface of the plated portion of the substrate 1 is calculated. Desired.

The electric mening liquid used in the present invention may have any composition, M1 composition. However, l! of polarization values for a series of known and unknown substrates. When it comes to illumination conditions, it is preferable that conditions such as plating ingredients, composition, temperature, stirring, etc. be constant.

The appropriate amount of air to be applied to the substrate 1 or 1 depends on the size of the effective surface area of the part to be polished. This ゛tunkij−
is usually the break in the polarization potential that occurs on the plate 1 or 1.
The l value is set to be in the range of 1ηl < 10 mV. The absolute value of polarization'i position is 1ηl>lomv7
This is because in the :l range, the relationship in formula (1) no longer becomes dispersive.

As is clear from the explanation in 1-1 below, the method for measuring the surface tni product of the present invention has the ability to measure the effective surface area of the part to be cleaned in the cleaning bath before starting electric cleaning, and 7 (after determining the surface area A111 by +,
It is highly efficient and practical because electroplating can be performed immediately; c) The equipment is simple and the cost required for the equipment is low; and (3) J-effect surface implantation on the plated part. It has the effect of being able to measure 11 degrees extremely quickly, and therefore easily determining the appropriate IL density. It is.

[Examples of the Invention] Example 1 First, a sulfuric acid steel plating bath having the following composition was prepared as a coating solution.

Next, the surface area in this plating solution was 2.5°4.
5.7.0 Using a capacitor with a similar arrangement, a Coulomb load of about η0 to 10 mV is applied to the substrate for an instant, and immediately after that, (the polarization of the plate is S, C).

Measurements were made with an open circuit fE, using the E11 pole as a reference electrode. For each surface area, the polarization value η. From formula (1)
Figure 2 shows the electric double layer capacitance (+7i) obtained using

[Fig.
1 (ii 4 responsibilityゝ1'1ri's 'ilp ki-Φlayer capacity Qiai (C:do) was 550 liters F/rev.

Next, a printed wiring board with an unknown surface area to be repaired is
- When the J-horn was immersed in the plating solution mentioned above and the same method as in 1- was used, the value of "it" was determined (Y83
It was 00 HiroF. (7) I-nao-wo-tri
I:tll'l! Ki-A6 Rino's upper air double iaide: i3
: (cd, ) 550, F/l: The effective surface area of the part to be polished, obtained by dividing by fi, is 15.1d.

In order to confirm the reliability of the measuring method of the present invention, the effective surface area of the plated part was determined by the Branimeter number 1111 + 1 (() is t4 - .5tm, which is the same as the value determined by the method of the present invention. In good agreement (1).

[Brief explanation of drawings]

FIG. 1 shows an example of the arrangement of a power source, a charging system, a working electrode, a reference electrode, and a counter electrode (9) in the couplant method used in the present invention. FIG. 2 is an explanatory diagram of the present invention showing the relationship between the effective surface area of the substrate and the electric -Φ Iai. 1 or Bi... Substrate 2... Reference electrode 3...
Counter electrode 4...Member tank 5...Condenser 6...'iL) &j7...Relay 8...Potential recording device〆・-■, J-;゛=-(j-i),□ 3″lhi V1

Claims (1)

[Claims] After immersing the substrate to be repaired in the 1F gas repair solution and instantaneously applying a predetermined amount of charge to the board, the polarization value of the board immediately after that is measured in an open circuit state, and electricity is removed from the polarization point I6. - A method of increasing the effective surface area of the plated portion of the substrate by removing the electric capacitance of the hair waste.